This is a U.S. original patent application which claims priority on Great Britain patent application No. 0110923.0 filed May 4, 2001.
This invention relates to a processing apparatus for processing photographic material. In particular, the invention relates to a processor in which the entire process is carried out in a single processing space.
Co-pending U.S. application Ser. No. 09/920,495 discloses a processor which consists of a rotating cylindrical drum operating as a single-use processing apparatus in which the entire process is carried out in the same vessel. A convenient method of heating the drum is by means of a hot air box. Other heating methods such as a water thermostat through which the lower part of the drum passes can also be used. Surface mounted heaters can also be used. In conventional processing machines having tanks containing the processing solutions the tanks are often made of a plastics material such as PVC. This is ideal because it is inert to processing chemicals and has low thermal conductivity. Thus an aqueous solution can be heated in a tank by means of an immersible cartridge heater. Tank volumes are usually of the order of a few liters and good temperature control can be achieved because PVC is a good insulator. A single use processing machine as disclosed in, for example, co-pending application Ser. No. 09/920,495, uses similar volumes to process film as those used to replenish large conventional tanks of the order of 6 ml/linear foot of 35 mm film. This means that a 36 exposure film is developed in a volume of about 30 ml. This is about a factor of 100 lower than a conventional tank. The problem to be solved for a single use device is that the volume of solution used for processing is small but the apparatus to hold the film and to contain the solution is relatively large. Thus a small volume of processing solution which is pre-heated to the desired temperature is spread over the film and the inner surface of the processing chamber. The processing chamber is also pre-heated to the desired temperature but because of the complex structure of the processing chamber, temperature non-uniformities can occur within it. These are transferred to the film and to the processing solution. This results in image non-uniformities which can be manifest as unwanted non-imagewise density changes over the film area.
The invention aims to solve the problems mentioned above by removing the temperature non-uniformities.
According to the present invention there is provided an apparatus for processing a photographic material comprising a chamber adapted to hold the material therein, means for introducing solution into the chamber, means for removing the solution from the chamber and means for rotating the chamber, wherein the chamber is made of a material having a thermal conductivity greater than 1.47xc3x9710xe2x88x923 Watt/cm/degree K.
The invention further provides an apparatus for processing a photographic material comprising a chamber adapted to hold the material therein, means for introducing solution into the chamber, means for removing the solution from the chamber and means for rotating the chamber, wherein the cross-section of the wall of the chamber is such that overall uniformity of temperature is maintained across the chamber.
The invention yet further provides an apparatus for processing a photographic material comprising a chamber adapted to hold the material therein, means for introducing solution into the chamber, means for removing the solution from the chamber and means for rotating the chamber, wherein the cross-section of the wall of the chamber is substantially uniform throughout.
The invention also provides a method of heating a processing chamber to an operating temperature, the chamber being located within an insulated housing, the method comprising the steps of heating the air within the insulated housing, directing the heated air in a direction away from the chamber, circulating the heated air throughout the housing and rotating the chamber within the heated air, the chamber thus being heated to a uniform temperature throughout.
Overall temperature control of the processing device can be improved by the invention.
The invention improves temperature uniformity throughout the processing space.
The invention improves the uniformity of processing conducted within the processing space.